feat: add more type hints

fastapi_cache/__init__.py

@@ -1,28 +1,29 @@
-from typing import Callable
+from typing import Callable, Optional, Type
 
+from fastapi_cache.backends import Backend
 from fastapi_cache.coder import Coder, JsonCoder
 from fastapi_cache.key_builder import default_key_builder
 
 
 class FastAPICache:
-    _backend = None
-    _prefix = None
-    _expire = None
+    _backend: Optional[Backend] = None
+    _prefix: Optional[str] = None
+    _expire: Optional[int] = None
     _init = False
-    _coder = None
-    _key_builder = None
+    _coder: Optional[Type[Coder]] = None
+    _key_builder: Optional[Callable] = None
     _enable = True
 
     @classmethod
     def init(
         cls,
-        backend,
+        backend: Backend,
         prefix: str = "",
-        expire: int = None,
-        coder: Coder = JsonCoder,
+        expire: Optional[int] = None,
+        coder: Type[Coder] = JsonCoder,
         key_builder: Callable = default_key_builder,
         enable: bool = True,
-    ):
+    ) -> None:
         if cls._init:
             return
         cls._init = True
@@ -34,31 +35,31 @@ class FastAPICache:
         cls._enable = enable
 
     @classmethod
-    def get_backend(cls):
+    def get_backend(cls) -> Backend:
         assert cls._backend, "You must call init first!"  # nosec: B101
         return cls._backend
 
     @classmethod
-    def get_prefix(cls):
+    def get_prefix(cls) -> Optional[str]:
         return cls._prefix
 
     @classmethod
-    def get_expire(cls):
+    def get_expire(cls) -> Optional[int]:
         return cls._expire
 
     @classmethod
-    def get_coder(cls):
+    def get_coder(cls) -> Optional[Type[Coder]]:
         return cls._coder
 
     @classmethod
-    def get_key_builder(cls):
+    def get_key_builder(cls) -> Optional[Callable]:
         return cls._key_builder
 
     @classmethod
-    def get_enable(cls):
+    def get_enable(cls) -> bool:
         return cls._enable
 
     @classmethod
-    async def clear(cls, namespace: str = None, key: str = None):
+    async def clear(cls, namespace: Optional[str] = None, key: Optional[str] = None) -> int:
         namespace = cls._prefix + (":" + namespace if namespace else "")
         return await cls._backend.clear(namespace, key)